Foam material dispensers have been developed including those directed at dispensing polyurethane foam precursor that are mixed together to form a polymeric product. The chemicals are often selected so that they harden following a generation of carbon dioxide and water vapor, and they have been used to form “hardened” (e.g., a cushioning quality in a proper fully expanded state) polymer foams in which the mechanical foaming action is caused by the gaseous carbon dioxide and water vapor leaving the mixture.
In particular techniques, synthetic foams such as polyurethane foam are formed from liquid organic resins and polyisocyanates in a mixing chamber (e.g., a liquid form of isocyanate, which is often referenced in the industry as chemical “A”, and a multi-component liquid blend called polyurethane resin, which is often referenced in the industry as chemical “B”). The chemicals are typically mixed in a mixing module, and the mixture can be dispensed into a receptacle, such as a package or a foam-in-place bag, where it reacts to form a polyurethane foam.
A typical mixing module includes inlet ports that introduce the various chemicals into the mixing module in producing the foam. Flow of the compounds from the inlet ports into the mixing module is generally controlled by a valve that can be actuated between open and closed positions. However, foam-in-bag machines typically do not include mechanisms designed to prevent the flow of the chemicals in the event of a power loss. For example, if the valve of a mixing module is in an open position (e.g., in a position where the chemicals are flowing so that the foam-in-bag machine is producing and dispense foam) when the machine loses electrical power, the valve of the mixing module would remain in this open position. Accordingly, the chemicals would continue to flow even after the machine has lost power, and the operator would be without means to stop the flowing chemicals and the foam. The uncontrolled flowing of chemicals and foam can cause the foam to overflow, and this can lead to a foam and chemical mess inside the machine, on the floor of the facility, and on the product that the operator was attempting to pack. It can also lead to a crossover of chemicals, as one chemical can migrate into the opposite side of the dispenser or vice versa.
Power losses that can lead to such a situation can be experienced for a variety of reasons. For example, the entire facility could lose power (e.g., a blackout, tripped breaker, etc.), the operator can initiate a shutdown (e.g., emergency shut down, etc.), a colleague can unexpectedly shut off the power (e.g., a practical joke, an emergency shut down, etc.), the power can be shut off accidentally (e.g., accidental removal of the plug, accidental initiation of shut down, etc.), or the like. Such a situation can require a protracted service call from a qualified technician to clean the mess and service the machine for running again. In addition to the costs of the service call, additional expenses may be required if parts need to be replaced. Further, expanded and hardened foam produced by the foam-in-bag machine can be tough to remove. Furthermore, these sorts of events can damage the operator's confidence in the foam-in-bag process, and may cause operator to search for alternative packaging materials and solutions.